1. Technical Field
The invention is related to a computer-implemented system and process for constructing a model of a 3D scene, and more particularly, to a system and process for refining a previously constructed model using one or more panoramic views of the scene.
2. Background Art
A great deal of effort has been expended on 3D scene reconstruction from image sequences (with calibrated or un-calibrated cameras, e.g., [FSL+95]) using computer vision techniques. Unfortunately, the results from most automatic modeling systems are disappointing and unreliable due to the complexity of the real scene and the fragility of the vision techniques. Part of the reason is the demand for accurate correspondences (e.g., point correspondence) required by many computer vision techniques such as stereo and structure from motion. Moreover, such correspondences may not be available if the scene consists of large un-textured regions.
Fortunately, for many real scenes, it is relatively straightforward to interactively specify corresponding points, or lines, or planes. For example, the interiors and exteriors of buildings provide vertical and horizontal lines, as well as parallel and perpendicular planes. These constraints have been exploited in several interactive modeling systems. For example, PhotoModeler (by Eos Systems Inc. of Vancouver, BC, Canada) is a commercial product which constructs 3D models from several images, using photogrammetry techniques and manually specified points. However, explicit camera calibration is necessary with this system. The TotalCalib system, on the other hand, estimates the fundamental matrix from a few selected matched points [BR97]. It then predicts other possible matching points from one image to others. In Becker's modeling system, the problem of lens distortion (encountered in images taken with wide field of view lenses) is also considered [BB95]. By employing the known structure of building exteriors, the Facade system directly recovers a solid 3D model (blocks) from multiple images [TDM96]. However, none of these systems employs panoramic images as does the present invention.
It is noted that in the preceding paragraphs, as well as in the remainder of this specification, the description refers to various individual publications identified by an alphanumeric designator contained within a pair of brackets. For example, such a reference may be identified by reciting, "reference [BR97]" or simply "[BR97]". Multiple references will be identified by a pair of brackets containing more than one designator, for example, [BR97, BB95, TDM96]. A listing of the publications corresponding to each designator can be found at the end of the Detailed Description section.